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Heads and Tails

StarDate:

November 13, 2010

When Leo, the lion, climbs into the sky, he charges head first. So do the celestial scorpion and the fishes -- the northern ones, anyway. But some sky creatures do it the other way around -- they back into the sky.

An example is the whale -- the constellation Cetus -- which spreads across the east and southeast at nightfall. The star that represents its tail climbs above the horizon before the star that represents its jaws.

The tail star is Deneb Kaitos. The name comes from an Arabic phrase that means “tail of the whale.” It’s fairly bright, and there are few other bright stars around it, so it’s fairly easy to pick out.

Like many of the stars that are visible to the unaided eye, Deneb Kaitos is a giant -- a star that has puffed up as it nears the end of its life. It’s many times the size of the Sun, and more than a hundred times brighter. And it’s close as stars go -- less than a hundred light-years away.

The star at the whale’s head is Menkar. The name means “the whale’s nose,” but in most depictions of the constellation, it represents the jaws.

Menkar is more than twice as far as Deneb Kaitos, and like the tail star, it’s also a giant. In fact, it out-giants Deneb Kaitos. It’s bigger and brighter, and it’s closer to the end of its life. Before long, it’ll become unstable, so it’ll pulse in and out like a beating heart -- a process that is already playing out in another star in Cetus. More about that tomorrow.

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